The present invention is directed to a tibial alignment guide assembly and a method of using a tibial alignment guide assembly during arthroplastic surgery of the knee, particularly for the extraction of tibial plateau fixation pins that hold the assembly in place as the tibial alignment guide is being positioned and fixed for tibial resection.
In replacing a knee joint, it is important that the bone at the proximal end of the tibia be removed or resected with respect to the mechanical axis of the tibia and taking into account the appropriate varus/valgus angle and flexion/extension angle for the knee joint. As resected, and with the femur resected, the resected end of the tibia can then receive a tibial implant and the resected end of the femur can receive a femoral implant to reconstruct the knee joint. Proper fit and function of the implant will depend on the accuracy of the resections. Therefore, a resection guide may be affixed to the tibia to direct a cutting instrument along the correct plane.
One method used for obtaining the correct bone cuts includes providing a tibial alignment guide assembly that is anchored relative to the tibia for alignment of the tibial resection. The tibial alignment guide assembly generally includes an ankle clamp mounted thereon for stabilizing a distal end of the tibial alignment guide assembly to the lower leg, i.e., ankle, and a means for anchoring an end of the tibial alignment guide assembly directly to the tibia. The latter usually includes at least one pin or spike extending outwardly from the tibial alignment guide assembly. With the ankle clamp secured to the ankle, the resection guide is brought proximate with the tibia. At this point, the at least one pin or spike is driven by impaction into the tibia thereby anchoring the tibial alignment guide assembly relative to the tibia. The resection guide may now be correctly aligned with the tibia, using the tibial alignment guide assembly as a reference.
The resection guide itself is next affixed to the tibia in a desired position, again using the tibial alignment guide assembly as a reference. Once the resection guide is affixed to the tibia, the rest of the tibial alignment guide assembly is removed so that the surgeon can make the various cuts to the proximal end of the tibia.
In order to remove the rest of the tibial alignment guide assembly, the ankle clamp is separated from the ankle and the fixation pin is extracted from the proximal end of the tibia. Extracting the fixation pin may include striking a part of the tibial alignment guide assembly with a hammer in order to dislodge the pin from the tibia or attaching and using a slap hammer to dislodge the pins.
Unfortunately, this method of extracting the fixation pin includes additional steps and instruments. The time and expense of the surgery is thus extended, and there is additional time involved in maintaining the additional instruments. Perhaps most importantly, an extraction hammer exerts an uncontrolled sudden force against the tibial alignment guide assembly, the excessive jarring may cause movement of the resection guide, thereby displacing it from its desired spatial relationship with the tibia. Even slight movement of the resection guide relative to the tibia may lead to resection in the wrong plane, or if noticed by the surgeon, the need for realignment of the resection guide.
Such a resection guide is shown in U.S. Pat. No. 6,090,114, the disclosure of which is hereby incorporated by reference herein.